The HOBO MX2501 pH and Temperature Data Logger is designed for long-term monitoring of pH in estuaries, lakes, streams, rivers, and oceans. Leveraging Bluetooth Low Energy® (BLE) technology, the MX2501 pH Logger communicates wirelessly with the free HOBOmobile® app on iOS devices making logger setup, calibration, and data offload quick and easy.
A guided pH calibration process on the HOBOmobile app makes an otherwise complicated process easier to follow. This affordable and compact logger dramatically cuts the time and effort needed to collect field data, while also offering higher resolution in data.
NOTE: pH electrodes should always be stored in storage solution when not deployed.
Guided pH calibration following on-screen prompts in HOBOmobile app
Rugged PVC housing for deployment in both freshwater and saltwater environments
Quick and easy data offload via Bluetooth Low Energy (BLE) to iOS and Android devices
Water detection system for longer battery life and less maintenance
Potentiometric pH electrode with plastic body, gel electrolyte, and double cloth junction
User-replaceable battery, pH electrode, and anti-biofouling copper guard
Accuracy of ±0.10 pH units within ±10°C of temperature at calibration
2.00 to 12.00 pH; -512 to 512 mV
±0.10 pH units within ±10°C of temperature at calibration; ±0.20 mV
0.01 pH; 0.02 mV
pH Response Time
1 minute typical to 90% at constant temperature in stirred water
-2° to 50°C
-2° to 50°C - non-freezing
To 40 m
Wireless Data Standard
Bluetooth Low Energy (Bluetooth Smart)
Approximately 30.5 m line-of-sight in air
1 second to 18 hours
One AA 1.5 Volt, user-replaceable
1 year typical at 25°C with logging interval of 1 minute and Bluetooth Always On selected in software. 2 years typical at 25°C with logging interval of 1 minute and Bluetooth Off Water Detect enabled in software. 3 years typical at 25°C with logging interval of 1 minute and Bluetooth Always Off selected in software.
pH Electrode Life
152 KB (43,300 measurements, maximum)
22.86 x 4.27 cm
Logger: PVC housing and sensor end cap, polycarbonate closure caps and mounting end cap with a TPE switch pH electrode: plastic-bodied with Pellon® junctions and gel electrolyte, glass pH sensor bulb